The present invention relates to bis-hydroxyphenyl menthane (BHPM) polyesters and polyester/polycarbonates and methods for making the same, for example from a phthalate and a bis-hydroxyphenyl menthane. Polyphthalate polyesters of this type can be made with desirable, high glass transition temperatures.
It is becoming of increasing interest to develop thermoplastics with high glass transition temperatures. Polycarbonates are a well known class of thermoplastics with several advantageous properties, such as high optical clarity and ductility. However, the glass transition temperatures of polycarbonates are limited. Bisphenol A polycarbonates exhibit a Tg of approximately 150xc2x0 C., while polyphthalate carbonate, a polyestercarbonate copolymer, exhibits a Tg of approximately 178xc2x0 C. Bisphenol I polycarbonates have a much higher Tg of approximately 220xc2x0 C., but some applications require even higher heat resistance. For instance, the preferred range for processing advanced LCD films is 250xc2x0 C. or higher. However, few thermoplastic materials can be processed into films by solvent casting and still possess the required heat performance, optical clarity, and ductility.
Bis-hydroxyphenyl menthanes are known in the art. For example, the synthesis of 4,4xe2x80x2-[1-methyl-4-(1-methyl-ethyl)-1,3-cyclohexandiyl]-bisphenol (i.e., 1,3-bis-hydroxyphenyl menthane, hereinafter xe2x80x9c1,3-BHPMxe2x80x9d) is disclosed in U.S. Pat. No. 5,480,959. A polycarbonate synthesized from 1,3-BHPM that possesses a Tg of 249xc2x0 C. is also disclosed.
The present invention provides BHPM polyesters and polyester/polycarbonates. In one embodiment of the invention, a polyester is provided comprising phthalate residues and BHPM residues, for example 1,3-BHPM residues or 2,8-BHPM residues. The phthalate residues may comprise either terephthalate residues or isophthalate residues or both. One embodiment of the method of the invention for producing a BHPM-polyphthalate polyester comprises the steps of:
(a) combining a phthaloyl chloride and 1,3-BHPM to form a reaction mixture that contains a polyphthalate polyester; and
(b) recovering the polyphthalate polyester from the reaction mixture.
By selection of the phthalate residues, polyesters with high glass transition tmperatures can be obtained.